The invention relates to the field of winches and in particular grip pulley winches. Grip pulley winches should not be confused with drum winches or the like. This is because winches with a grip pulley have the characteristic of being usable with cables of unlimited length due to the selected principle of gripping the cable within a single groove of the grip pulley in which the cable is wrapped around at least one turn.
Such winches have been developed for professional, safety and sporting purposes: access to building façades, masts for wind turbines or ships, working areas in lift shafts or silos, mountain rescue and climbing, etc. They have the following advantages over other winches:                no height limit        the winch can move along the cable and therefore accompany the load, whether this is an object or a user.        
EP 1 030 726 for example describes a grip winch comprising a motor, the drive shaft of which is coupled to a pulley with a single V groove, mounted on a frame. The winch comprises a locking member attached to the frame which allows the winch to climb the rope and locks as soon as the climbing force ceases. A guide ring is positioned above and close to the pulley. The rope is placed by the user in such a way as to pass through the guide ring, wrap around the pulley and pass once more through the same guide ring, the rope therefore being engaged around 180° in the pulley groove. The design of the pulley part of this winch, with a contact angle of 180°, entails the need for a locking member. Another disadvantage is associated with the taut strand and the slack strand necessarily passing through the guide ring, which involves the rope entering and exiting via the top of the winch. In the case of a rope, which does not have the longitudinal stiffness of a cable, upwards extraction may prove problematic and cause jamming.
Other devices using grooved pulleys for hauling may be cited. Le GB 2057871 describes, for example, a life-saving device for lowering people by abseiling comprising a frame, to be attached to the person to be lowered, and a grooved pulley for the cable, the latter being guided around the pulley over an angle of greater than 180 degrees. The pulley is braked by a mechanism which takes account of the person's weight.
GB 2057871 describes a winch of the boat winch type, for hauling sails. EP0876987 describes an emergency lift system intended to be installed on the outside of a building. WO2010049597 describes a self-blocking, anti-panic and position-locking belaying/descending device.